What's in your air?

May 09, 2014 by Denise Brehm
Katie Spies works on the internal wiring on a CLAIRITY node. Credit: Eben Cross

Every senior at MIT has come to know the campus in a personal way, having established favorite haunts for studying, eating, resting, and playing during their four years at the Institute. But the Course 1 Class of 2014 is getting to know the campus on an even more intimate level, and wants to share that with others.

These students in the MIT Department of Civil and Environmental Engineering (CEE) just completed deployment of a highly sophisticated monitoring network that covers most of the 0.25-square-mile campus. The network, called CLAIRITY, has 24 indoor and outdoor sensor nodes that continuously measure gases and the small particles found in and send these data via wireless to a central computer. They formally launched the network and its web portal in a public presentation May 6 in Room 46-3002.

The network represents two semesters of work for the students, who designed, built, and deployed the network as the capstone project in the CEE engineering design subject. They worked at Beaver Works, a joint facility of MIT Lincoln Lab and MIT's School of Engineering, located in Technology Square.

Air-quality networks like CLAIRITY, and other new types of innovative infrastructure, provide information essential to the design of smarter cities, a major goal of civil and environmental engineers.

"This project exemplifies the very best in our students, to take a project from an idea, to a plan, to implementation," says CEE department head Markus Buehler, a professor of civil and . "I congratulate the Class of 2014 on this major accomplishment, and am excited about the potential impact of this new technology."

Smart cities need better air-quality monitoring

Air pollution is the leading environmental cause of premature death and a major contributor to chronic illness like asthma, particularly in congested urban areas with dense vehicle traffic. This is true in U.S. cities and even more so in many developing countries where the rapid rise in automobile use is leading to dangerously high levels of airborne particles and gases.

Graphic showing a CLAIRITY node without the 3-D printed casing.Credit: CLAIRITY Hardware Team

In the United States, the Environmental Protection Agency (EPA) monitors air quality by measuring levels of particulate matter and gases defined by the Clean Air Act. In Massachusetts, the Department of Environmental Protection (DEP), following EPA protocols, has deployed sensors at 28 monitoring stations strategically placed across the commonwealth. Five of these monitoring stations are in Boston. Most cities, including Cambridge, have no DEP monitoring stations.

Thanks to the CEE students, the MIT campus now has its own network that provides extremely high-resolution, precise data—each sensor is calibrated using a state-of-the-art lab system—on par with the DEP monitoring stations. But a monitoring station in the DEP's statewide network is more than 50 times as expensive as nodes in the CLAIRITY system, each of which cost only $1,500 to build.

The MIT network measures ozone, carbon monoxide, nitric oxide, nitrogen dioxide, and small particles like soot, dust, and pollen that can increase risk of lung and heart disease. The web portal shows a map indicating air health at each node, and displays data from one or more sensor nodes as a graph, in time intervals of the user's choice, and makes these data downloadable as a CSV file. The site automatically refreshes every 10 seconds.

CLAIRITY reports that air on the Cambridge campus is relatively clean. The network picked up the occasional blast of gas and particles related to heavy vehicle traffic at certain points in the day – events that standard hourly monitors tend to average out, rather than report. It also recorded bursts of pollution at some indoor nodes, as well as outdoor pollution events that affected the entire Boston area.

The inexpensive network—now operational—could serve as a template for air-quality monitoring in other cities, even the more polluted cities throughout the developing world.

A CLAIRITY node deployed at the Kresge parking lot. Credit: Eben Cross

Hands-on project from start to finish

The students conceived of the project, created the initial design, and built the first prototype of their sensor node in the fall 2013 semester. This spring they fine-tuned the design, purchased the parts, assembled the gas sensors, placed a commercial laser particle sensor and microprocessor on each node, and then 3-D printed the housing for the sensors, as well as the weather-protection casing that covers the entire node.

"The seniors really rose to the challenge of this class, dedicating extensive time and energy to learning new skills and working through a problem from design to implementation and all the hiccups along the way," says associate professor Colette Heald, who taught the class with lecturer Eben Cross and associate professor Jesse Kroll. "This network is a tremendous accomplishment, and something that we hope will be a part of the legacy of the CEE Class of 2014."

The class divided into five teams, each with primary responsibility for one aspect of the project. The hardware team selected, purchased, designed and 3-D printed, and assembled the . The software team wrote the code used by each Raspberry Pi microprocessor to decipher data and forward it to the central computer. The calibration team translated voltage into concentration volumes, and then calibrated the continuous sensor data against high-fidelity instruments. Students on the deployment team installed all 24 nodes, and wired them to power connections. The communications team built and populated the and translated data into easily understandable formats.

Daphne Basangwa, a member of the hardware team, says that "seeing the different teams' representatives working together to reach a common goal" and "knowing this is how it will work in real life" injected the project with a sense of reality.

"Just keeping track of the email threads from all the people involved" in installing the 24 nodes was a challenge, says Linda Seymour, a member of the deployment team. "But the people we're working with on installation are great. We're meeting some of the people who make MIT function, like the electricians and the people who run the Tech shuttle."

Explore further: Smart sensor technology to combat indoor air pollution

add to favorites email to friend print save as pdf

Related Stories

Smart sensor technology to combat indoor air pollution

Apr 14, 2014

Indoor air quality (IAQ) influences the health and well-being of people but for the last 20 years there has been a growing concern about pollutants in closed environments, the difficulty in identifying them ...

Low-cost sensors gather air pollution data

Nov 26, 2013

(Phys.org) —Epidemiologists' understanding of the relationship between exposure to airborne pollutants and a range of health conditions, such as cardiovascular disease and asthma, has grown increasingly ...

Cambridge to host first city-wide wireless sensor network

Apr 05, 2007

Harvard University, BBN Technologies, and the City of Cambridge have begun a four-year project to install 100 wireless sensors atop streetlights in Cambridge, Mass., creating the world's first city-wide network of wireless ...

India admits 'Delhi as polluted as Beijing' (Update)

May 08, 2014

India's state air monitoring centre made a rare admission Thursday that pollution in New Delhi was comparable with Beijing, but disputed a WHO finding that the Indian capital had the dirtiest atmosphere in ...

Air quality worsening in world's cities

May 07, 2014

Most city dwellers around the world are exposed to air pollution levels that are considered unsafe, and the situation is getting worse, according to a World Health Organization report Wednesday.

Monitoring air quality takes next step

Mar 31, 2014

With air pollution linked to millions of deaths around the world, it has never been more important to monitor the air we breathe. Today marks a significant step forward as a deal is secured to build a crucial ...

Recommended for you

Augmented reality helps in industrial troubleshooting

Aug 28, 2014

At a "smart" factory, machines reveal a number of data about themselves. Sensors measuring temperature, rotating speed or vibrations provide valuable information on the state of a machine. On this basis, ...

User comments : 0